Case ReportImageless Navigation Improves Intraoperative Monitoring ofLeg Length Changes during Total Hip Arthroplasty for Legg-Calve-Perthes Disease: Two Case Reports

Ritesh R. Shah,1,2,3 Varsha Gobin,4 and Jeffrey M. Muir 5

1Department of Orthopedic Surgery, Illinois Bone & Joint Institute, Morton Grove, IL, USA2Department of Orthopedic Surgery, Advocate Lutheran General Hospital, Park Ridge, IL, USA3Department of Orthopedic Surgery, NorthShore University HealthSystem-Skokie Hospital, Skokie, IL, USA4Department of Psychology, Faculty of Science, University of Waterloo, Waterloo, ON, Canada5Intellijoint Surgical, Waterloo, ON, Canada

Correspondence should be addressed to Jeffrey M. Muir; j.muir@intellijointsurgical.com

Received 26 January 2018; Accepted 14 June 2018; Published 9 July 2018

Academic Editor: Bayram Unver

Copyright © 2018 Ritesh R. Shah et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Legg-Calve-Perthes disease is a rare condition characterized by avascular necrosis and malformation of the femoral head. For manypatients, total hip arthroplasty (THA) is the only viable treatment option; however, there are challenges associated with THA in thispopulation, primarily the equalization of leg lengths. Here, we present two cases of Legg-Calve-Perthes disease treated via total hiparthroplasty with the assistance of an imageless, computer-assisted navigation device. In each case, the device providedintraoperative data on leg length in real time, allowing for improved accuracy of component placement. Postoperative leglengths were confirmed to be equalized in each case using radiographs. These cases are, to our knowledge, the first such casesusing imageless navigation during THA and demonstrate the benefits of such assistive technologies in challenging cases such asLegg-Calve-Perthes disease.

1. Introduction

Legg-Calve-Perthes disease (LCPD) is a relatively rarechildhood disorder, occurring in between 0.4/100,000 and29.0/100,000 children per year under age 15 years [1].Often idiopathic in onset, LCPD is characterized by deforma-tion and flattening of the femoral head due to avascularnecrosis [2, 3], with patients experiencing symptoms rangingfrom leg length discrepancy (LLD) to premature osteoarthri-tis [2, 4–6]. Although initial treatment plans are numerousand include both conservative and surgical methods, therate of success of such treatment is low and in many cases,effective pain relief remains elusive [2, 6].

The long-term prognosis for LCPD is poor and oftenincludes a diagnosis of secondary hip osteoarthritis and signif-icant leg length discrepancies which in turn result in a multi-tude of biomechanical complications including low back pain,knee and groin pain, and compensatory contralateral hip pain

[6]. In many patients, total hip arthroplasty (THA) is the onlyviable treatment option; however, THA for LCPD is the sub-ject of much debate, with some authors suggesting that LCPDpatients undergoing THA bear higher risks than other THApatients and that the likelihood of unsatisfactory results fol-lowing THA is higher in LCPD patients [6, 7]. Increased ratesof revision surgery and a higher frequency of femur fracturesand motor nerve palsies due to the technical challenges asso-ciated with THA in this population are the primary concernsfor LCPD patients; however, equally challenging for surgeonsis the equalization of leg lengths [6, 8], the failure of which isthe most common reason for litigation against orthopedicsurgeons [9]. As such, there is a need for improvements inpatient-related outcomes following THA in this population.

Computer-assisted navigation is an increasingly com-mon adjunct to THA and has demonstrated the ability toimprove the accuracy of leg lengthening [10, 11]. There are,however, few studies reporting the use of this technology in

HindawiCase Reports in OrthopedicsVolume 2018, Article ID 4362367, 4 pageshttps://doi.org/10.1155/2018/4362367

THA in patients with LCPD. Here, we report 2 cases of THAfor LCPD performed with the assistance of an imagelesscomputer navigation system.

2. Case Presentation

2.1. Case 1. A 38-year old male presented with a chief com-plaint of chronic and worsening left hip pain. The patientreported a lifelong history of pain and disability anddescribed his current pain as sharp, aching, burning, severe,and constant, occurring daily. Relevant history included adiagnosis of hip dysplasia at age 1 year and confirmationof Legg-Calve-Perthes disease at age 18. The patient walkedwith a significant limp and reported difficulties with activi-ties of daily living such as putting on socks and shoes andpain on getting out of bed. He also reported the use of aheel lift to equalize his leg lengths and expressed frustrationat his daily pain. He had attempted to manage his pain withhome exercise, activity modification, strengthening, anti-inflammatories, ice, and rest at length, all without success.

On physical examination, the left leg was significantlyshorter, with the leg length discrepancy measured grossly atapproximately 2.5–3.0 cm. Range of motion (ROM) of lefthip was decreased and measured as follows: 0–85° of flexion,5° of internal rotation in flexion (IRF), 5° of external rotationin flexion (ERF), 30° of abduction, and 5° of adduction.Abductor strength was 4/5 bilaterally. Neurological examina-tion was unremarkable.

Radiographs revealed left hip dysplasia with upsloping ofthe acetabular socket. LCPD affecting the femoral head wasconfirmed, with an incompletely formed femoral head notedand a leg length discrepancy measured at 2.5 cm.

The preoperative plan included left hip total hip arthro-plasty. Imageless, computer-assisted navigation was usedduring surgery to assist with leg length equalization andcomponent placement (off-label use).

Surgery was successful and at three weeks postprocedure,the patient was progressing well, had experienced significantpain relief, and was satisfied with his surgery. Left hip rangeof motion was improved, most notably in flexion and ERF.Postoperative ROM was measured at 0–95° flexion, 5° IRF,30° ERF, 30° abduction, and 10° adduction. Radiographs

revealed that the left hip was well aligned and concentricallyreduced. The left leg was lengthened by 2.5 cm, and leglengths were even (Figure 1).

2.2. Case 2. A 47-year old female presented with a chiefcomplaint of severe right-sided hip pain that was chronic innature. Relevant history included right hip surgery at 10years of age to address symptoms of Legg-Calve-Perthesdisease. She reported no relief from this procedure and inthe interim, had sought relief through multiple conservativetreatments without success. The patient also reportedchronic low back pain, contralateral knee pain, and right-sided groin pain and thigh pain which she attributed to asignificant LLD.

On physical examination, the right leg was significantlyshorter, with a noticeable LLD present. Range of motion ofright hip was decreased and measured as follows: 0–80° flex-ion with significant pain at end range, 5° IRF with significantpain, 5° ERF, 20° abduction, and 10° adduction. Abductorstrength was 4/5 bilaterally. On orthopedic testing, anteriorimpingement test, Patrick-FABERE, and lateral impinge-ment tests were all positive on the right. Neurological exam-ination was unremarkable.

Radiographic examination revealed a 3.5 cm LLD withthe right leg shortened, ovoid femoral head, joint spacenarrowing, sclerosis, osteophytes, acetabular dysplasia, short-ened femoral neck, and trochanteric overgrowth. Diagnosesof Legg-Calve-Perthes disease and secondary osteoarthritiswere confirmed.

The preoperative plan included a right hip total hiparthroplasty. During surgery, computer-assisted navigationwas again used to assist with component placement andmonitoring of changes in leg length (off-label use).

Surgery was successful and at three weeks postprocedure,the patient reported significant pain relief and was satisfiedwith the outcome of her surgery. She reported the use of acane when walking long distances but was otherwise ambu-lating without the use of assistive devices and was progres-sing well in physical therapy. Range of motion hadimproved, most significantly in flexion, ERF, and abduction,and was measured at 0–95° flexion, 5° IRF, 30° ERF, 35°

abduction, and 5° adduction. Radiographs revealed equalized

(a) (b)

Figure 1: Pre- (a) and postoperative (b) radiographs for Case 1. Preoperatively, the LLD was estimated at 2.5 cm. Leg lengths were equalizedpostoperatively.

2 Case Reports in Orthopedics

leg lengths and implants that were well aligned and concen-trically reduced (Figure 2).

3. Discussion

Legg-Calve-Perthes disease is a challenging condition forphysicians, as conservative treatments and early surgicalinterventions are largely temporary and THA is oftenrequired in the long term. THA in this population, however,can be technically difficult and complex, with the potentialfor complications such as femoral fracture and motor nervepalsies [4–6]. Moreover, previous childhood surgeries relatedto LCPD often alter proximal femoral anatomy and maycomplicate component implantation during THA [8, 12].Given the additional risks and complications associated withTHA in patients with LCPD, there is a potential role forassistive technologies in this surgical population.

The cases presented in this report utilized an imageless,computer-assisted navigation system (Intellijoint HIP®,Intellijoint Surgical Inc., Waterloo, ON) to provide real-time intraoperative data regarding acetabular cup positionand changes in leg length, data that was integral in equalizingleg lengths during surgery. To our knowledge, this marks thefirst such use of imageless navigation in LCPD-related THA.In both cases, a large preoperative LLD was present. Postop-eratively, radiographic analysis confirmed that leg lengthswere equalized. The ability of the navigation device to pro-vide accurate intraoperative data was key in ensuring equalleg lengths postoperatively. The navigation device allowedfor real-time feedback and increased the ability of the sur-geon to accurately place components, thus decreasing thelikelihood of unsatisfactory postoperative results. Given theprevalence of LLD in LCPD and the impact of its associatedsequelae on patients’ functional abilities, the ability to equal-ize leg lengths postoperatively is paramount. Furthermore, ifLLD is not corrected accurately during primary THA, theresulting pain and functional impairment may require costlyrevision surgery to equalize leg lengths [13].

The biomechanical complications of LLD in LCPD arecompounded by potentially significant complications suchas growth plate disruption, which can further exacerbate legshortening and increase the likelihood of a chronic limp

[14]. Additionally, the high rate of neurological complica-tions associated with THA in this patient population is alsoa concern [12], with such complications thought to be relatedto inadequate soft tissue release or excessive limb lengtheningdue to poor preoperative planning [12]. The use of assistivetechnologies may help to mitigate these concerns, as itprovides feedback in real time, allowing the surgeon to alterpreoperative plans based on intraoperative data. Finally, thedevice used in the presented cases is a new technology, onethat is portable and does not require large equipment oroperating room alterations, making the technology cost-effective [10]. In the current climate of increasing healthcarecosts, cost-effectiveness and the potential to save costs bydecreasing the likelihood of revision surgery are importantfactors in surgeon and facility decision-making.

4. Conclusion

This report summarizes two cases of Legg-Calve-Perthes dis-ease treated with the assistance of an imageless, computer-assisted navigation device. The device provided intraoperativemeasurements of leg lengthwhich allowed improved accuracywith component placement and improved outcomes follow-ing surgery but limiting the likelihood of a postoperative leglength discrepancy.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Acknowledgments

The authors wish to thank Nancy Cipparrone, MA, for herassistance in gathering the clinical information and provid-ing editorial feedback.

References

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(a) (b)

Figure 2: Pre- (a) and postoperative (b) radiographs of Case 2. Preoperative LLD was measured at approximately 3.5 cm. Postoperatively, leglengths were equalized.

3Case Reports in Orthopedics

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[10] W. Paprosky and J. M. Muir, “Intellijoint HIP®: a 3D mini-optical navigation tool for improving intraoperative accuracyduring total hip arthroplasty,” Medical Devices: Evidence andResearch, vol. 9, pp. 401–408, 2016.

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